Undercut crankshaft hardening coil

ABSTRACT

Improved induction heating methods are presented for induction hardening undercut fillets of crankshafts or other workpiece recesses or undercuts in which an active turn is energized to induce current in a passive turn translated toward a workpiece undercut for heating the undercut.

REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/484,422, filed Jun. 15, 2009 and claims priority to and the benefitof U.S. Provisional Patent Application Ser. No. 61/061,371, filed Jun.13, 2008, entitled IMPROVED UNDERCUT CRANKSHAFT HARDENING COIL, theentireties of which applications are hereby incorporated by reference.

FIELD OF THE INVENTION

The present disclosure relates generally to the induction heating andmore particularly to improved undercut crankshaft hardening coilapparatus and methods for hardening undercut crankshafts.

BACKGROUND

Modern large crankshafts for use in locomotives or other high torqueapplications are often undercut into the side wall, creating a recess.Although this offers an improved crankshaft for the application itpresents a difficult challenge to properly heat treat the surface of theundercut. Descriptions of the undercut crankshaft hardening applicationsare found in U.S. Pat. Nos. 6,399,928 by Gezarzick et al and 7,145,115by Zahn et al., which are incorporated herein by reference. Thosedisclosures required complex electrical connections and or coilconfigurations to engage both the undercut fillets and the journal toallow the part to be heated with one continuous process.

SUMMARY

One or more aspects of the disclosure are now summarized to facilitate abasic understanding of the disclosure, wherein this summary is not anextensive overview of the disclosure, and is intended neither toidentify certain elements of the disclosure, nor to delineate the scopethereof. The primary purpose of the summary, rather, is to present someconcepts of the disclosure in a simplified form prior to the moredetailed description that is presented hereinafter. The presentdisclosure relates to improvements in induction heating coil assembliesand methods for induction hardening undercut fillets which may beemployed for hardening crankshafts or other workpieces having recesseswith undercut areas. The disclosed apparatus provides an active turn forheating a journal area in the workpiece recess and one or more passiveturns which are translated toward undercut fillets after the coilassembly is moved toward the recess with coupling portions of thepassive and active turns coupling energy from the active turn to thepassive turn(s) for heating the undercut fillets.

In accordance with one or more aspects of the disclosure, an inductioncoil apparatus is provided, having a coil assembly comprised of anactive turn and one or more passive turns. The active turn is coupleableto an electric power source to form a first conductive circuit includingone or more active coupling sections and one or more crossover sections.When the assembly is located near a workpiece and energized, thecrossover section(s) heat at least a portion of a journal area in aworkpiece recess. The passive turn is electrically isolated from theactive turn and forms a second conductive circuit including at least onepassive coupling section and at least one passive heating section. Thepassive turn is translatable relative to the active turn between a firstposition for engaging with or disengaging from the workpiece in whichthe passive heating section clears a recess sidewall, and a secondposition in which the passive coupling section is proximate to andelectromagnetically coupled with the active coupling section of theactive turn and in which the passive heating section is locatedproximate to an undercut fillet area of the workpiece recess. In thesecond position, energy from the active turn is electromagneticallycoupled to induce current in the passive turn(s) for fillet heatingwhile the journal area is heated by the active turn.

In certain embodiments, the active turn includes a circumferentialactive heating portion proximate the journal area.

In certain embodiments, the passive turn is translatable relative to theactive turn in a direction parallel to a longitudinal axis of theworkpiece between the first and second positions.

In certain embodiments, an insulator is disposed between the passivecoupling section and the active coupling section.

In certain embodiments, the passive heating section of the passive turnis located at least partially within the undercut fillet area of theworkpiece recess in the second position.

Further aspects of the disclosure provide a method for hardeningundercut fillets of a workpiece using induction heating. The methodincludes translating a coil assembly radially toward a recess in theworkpiece such that a passive turn of the coil assembly clears asidewall of the recess and at least one crossover section of an activecoil of the coil assembly is proximate a journal area in the workpiecerecess, translating the passive turn relative to the active turn suchthat a passive coupling section of the passive turn is proximate to andelectromagnetically coupled with an active coupling section of theactive turn and a passive heating section of the passive turn is locatedat least partially within an undercut fillet area of the workpiecerecess, and energizing the active turn with electrical power to heat atleast a portion of a journal area in the workpiece recess using the atleast one crossover section of the active coil and to induce electricalcurrent in the passive turn to heat at least a portion of the undercutfillet area of the workpiece recess using the passive heating section ofthe passive turn. In certain implementations, translation of the passiveturn relative to the active turn comprises translating the passive turnin a direction parallel to a longitudinal axis of the workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and drawings set forth certain illustrativeimplementations of the disclosure in detail, which are indicative ofseveral exemplary ways in which the principles of the disclosure may becarried out. The illustrated examples, however, are not exhaustive ofthe many possible embodiments of the disclosure. Other objects,advantages and novel features of the disclosure will be appreciated fromthe following detailed description of the disclosure when considered inconjunction with the drawings, in which:

FIGS. 1-4 are partial perspective, side and end elevation, and top planviews illustrating conductor portions of an exemplary coil assembly withan active turn and two passive turns in extended second positions inaccordance with one or more aspects of the present disclosure;

FIG. 5 is a simplified end elevation view of the coil assembly of FIGS.1-4 illustrating the passive turns in first retracted positions forclearance during radial insertion to or extraction from a workpiecerecess;

FIG. 6 is a simplified end elevation view of the coil assembly of FIGS.1-5 illustrating the passive turns in second extended positions forundercut fillet heating;

FIG. 7 is a simplified partial end elevation view of the coil assemblyof FIGS. 1-6 with the passive turns in first retracted positionsillustrating insertion of the assembly into a recess of a crankshaftworkpiece;

FIG. 8 is a simplified partial end elevation view of the coil assemblyof FIGS. 1-7 illustrating the passive turns axially extended to secondpositions for induction heating of the undercut fillet areas of theworkpiece recess;

FIG. 9 is a simplified partial end elevation view of the coil assemblyof FIGS. 1-8 illustrating the position of an exemplary crossover portionof the active turn proximate a journal portion of the workpiece recessduring induction heating;

FIGS. 10 and 11 are partial side and end elevation views of the coilassembly of FIGS. 1-9 illustrating magnetic laminations installed forelectromagnetic coupling and further details of an exemplary supportstructure;

FIG. 12 is a simplified end elevation view of another exemplaryembodiment of the coil assembly with a single passive turn in a firstretracted position for clearance during radial insertion to orextraction from a workpiece recess for heating single undercut fillets;

FIG. 13 is a simplified end elevation view of the coil assemblyembodiment of FIG. 12 illustrating the passive turn in a second extendedposition for undercut fillet heating;

FIG. 14 is a simplified partial end elevation view of the coil assemblyof FIGS. 12 and 13 with the passive turn in the first retracted positionillustrating insertion of the assembly into a recess of a crankshaftworkpiece;

FIG. 15 is a simplified partial end elevation view of the coil assemblyembodiment of FIGS. 12-14 illustrating the passive turn axially extendedto a second position for induction heating of the undercut fillet areaof the workpiece recess;

FIGS. 16 and 17 are partial end elevation views illustrating anothercoil assembly embodiment in which the passive turns are pivotallytranslatable between first retracted positions for insertion or removaland second extended positions for undercut fillet heating in accordancewith the disclosure.

DETAILED DESCRIPTION

Referring now to the figures, several embodiments or implementations arehereinafter described in conjunction with the drawings, where likereference numerals are used to refer to like elements throughout, andwhere the various features are not necessarily drawn to scale. Thepresent disclosure provides apparatus 2 and coil assemblies 4 thereofhaving an active turn 10 that couples with one or more fillet hardeningpassive turns 20, 21 and couples with a workpiece journal for hardeningthe journal 102 and also providing the energy to the two passive turnsor coils to harden one or more undercut fillet areas 104 of theworkpiece 100. The disclosed approach advantageously locates the activeturn crossovers 10 c, 10 e so as to inductively heat the journal 102,and the active turn 10 can extend around a circumferential portion ofthe journal by up to about 180 degrees. The active turn 10, moreover, iselectrically connected to a power supply to conduct current from thesupply for inductively heating the journal 102 via the crossovers. Oneor more inner passive turns 20, 21 are provided in at least one spacewithin and/or below the active turn 10 in certain embodiments, where thepassive turns 20, 21 are passively energized via electromagneticcoupling from the active turn 10 such that the passive turns 20, 21 arenot connected to the power supply, where the passive turns 20, 21 eachform a closed loop structure. A coupling portion 20 a, 21 a of eachpassive turn 20, 21 is proximate the circumferential and/or othercoupling portion 10 b, 10 f, 10 d of the active turn 10 so as toelectromagnetically couple therewith, and a second portion 20 c, 21 c ofthe passive turn 20, 21 is extendable at least partially into anundercut of a fillet 104 for heating thereof. In certain journalportions 104 of a crankshaft workpiece 100 having two undercut fillets104 at two axially spaced sides of the journal 102, each side can haveone or more passive heating turns or turn portions for heating theassociated fillet 104, with the passive turns 20, 21 of each side beingaxially movable at least partially into the undercut fillet areas 104after radial approach of the coil arrangement 2 to or proximate thejournal 102.

Referring initially to FIGS. 1-11, an exemplary induction coil apparatus2 is illustrated, which may be advantageously employed for hardeningundercut fillets 104 of a crankshaft or other workpiece 100. Oneembodiment is best shown in FIGS. 1-4, where the apparatus 2 has a coilassembly 4 including an active turn or coil 10 and two passive turns orcoils 20 and 21. The active turn 10 is coupleable using conductivecouplings 11 and 12 to an electric power source to form a firstconductive circuit therewith, where the active turn is formed of hollowcopper tube structures to provide an internal fluidic path forcirculation of coolant during operation via the couplings 11 and 12.Likewise, the first and second passive turns 20 and 21 are formed ofconductive (e.g., copper) tubes providing internal coolant passagewaysfor coolant circulated via coolant couplings 40. The active turn 10 ofFIGS. 1-11 is formed of sections 10 a-10 g including active couplingsection 10 b, a first active crossover section 10 c, a second activecoupling section 10 d, a second crossover section 10 e, another partialcoupling portion 10 f and a final portion 10 g, where the crossoversections 10 c and 10 e are operative to heat all or a portion of theworkpiece journal area 102 in a recess 110 thereof when the coilassembly 4 is positioned at or near the workpiece 100, as shown in FIG.9.

The first passive turn 20 is electrically isolated from the active turn10 and forms a closed conductive circuit including a circumferentialcoupling section 20 a, a crossover portion 20 b, a passive heatingsection 20 c, and a second crossover portion 20 d connecting back to thecoupling portion 20 a. Similarly, the second passive turn 21 forms aclosed conductive circuit electrically isolated from the active turn 10via coupling section 21 a, crossover sections 21 b and 21 d and anoutlying heating section 21 c, and the passive turns 20 and 21 areseparately cooled by fluid provided via tubes 40. The active and passiveturns 10, 20, and 21 are fitted with lamination keeper structures 30 forlaminations 42 (FIGS. 10 and 11) for electromagnetic coupling of theactive turn 10 with the passive turns 20 and 21, where any suitablemagnetic material may be used for the laminations 42, such as iron inone embodiment. Other embodiments are possible using suitable magneticmaterial to form flux concentrator structures 42, which need not belaminations. As shown in FIGS. 10 and 11, moreover, the coil apparatus 2further includes protective outer covers 50 and may include othersuitable mounting and support structures for translation operation asdescribed herein.

Referring also to FIGS. 5-9, the passive turns 20 and 21 aretranslatable by any suitable mechanical translation devices (not shown)relative to the active turn 10 between a first position (FIGS. 5 and 7)in which the passive heating sections 20 c and 21 c clear sidewalls 108of a workpiece recess 110 as the coil assembly 4 is translated radiallytoward the recess 110 (FIG. 7) and a second position (FIGS. 6 and 8 inwhich the passive coupling sections 20 a, 21 a are proximate to andelectromagnetically coupled with the first active coupling section 10 b,10 f, 10 d of the active turn 10. As shown in FIG. 8, moreover, aninsulator 26 may be provided in certain embodiments between the passivecoupling section 20 a and the active coupling section 10 b, 10 f, aswell as between the active coupling section 10 d and the passivecoupling section 21 a of the second passive turn 21, which may be anysuitable insulator material, such as Teflon in one example. In thesecond positions, moreover, the first passive heating section 20 c islocated at least partially within a first undercut fillet area 104 ofthe workpiece recess 110, and the second passive heating section 21 c islocated at least partially within a second undercut fillet area 104 ofthe workpiece recess 110, as illustrated in FIG. 8. In addition, asshown in FIG. 9, the active turn crossover portions 10 c and 10 e aredisposed to be proximate the workpiece journal portion 102 duringinduction heating when the apparatus 2 is translated toward the recess110.

In the embodiment of FIG. 8, the first passive turn 20 is translatablerelative to the active turn 10 in a first direction (to the left in thefigure) generally parallel to a longitudinal workpiece axis 8 betweenthe first and second positions, and the second passive turn 21 istranslatable in a generally opposite axial direction (to the right)between its first and second positions, where any suitable mechanism(s)can be used to provide the translation of the passive turns 20, 21relative to the active turn 10.

The current in the closely coupled fillet hardening active turns 20, 21will be equal (except for leakage flux) and opposite to the current inthe main active turn 10 in the illustrated embodiments. As a result, thecurrent in the fillet hardening portions 20 c and 21 c is in the samedirection as the main driving current of the active turn 10, and thecurrent induced in the fillets 104 is in the same direction as the mainjournal hardening current of the active turn crossover portions 10 c and10 e so that the net electromagnetic configuration is that of a standardcrankshaft hardening coil. With this arrangement, the fillet hardeningpassive sections 20 c and 21 c can be freely moved, at least partially,into and out of the fillet without any external electrical connection.As shown in FIG. 11, moreover, bumpers or guides 52 may be provided inthe apparatus 2 for locating the apparatus 2 relative to a workpiece100, which will generally be rotated about the axis 8 during heatingwith the active turn 10 energized. In addition, the apparatus and thecoil assembly 4 thereof may extend any circumferential distance aboutthe workpiece 100, such as about 180 degrees or less in variousembodiments.

Referring now to FIGS. 16 and 17, the translation of the passive turns20 and 21 need not be strictly parallel to the workpiece axis 8. In theembodiment of FIGS. 16 and 17, the passive turns 20 and 21 are pivotallytranslatable between first retracted positions for insertion or removalof the apparatus 2 while clearing the sidewalls 108 (FIG. 16), andsecond extended positions for undercut fillet heating (FIG. 17).

Referring now to FIGS. 12-15, another exemplary embodiment of the coilassembly 4 is illustrated, having a single passive turn 20 configuredgenerally as described above, along with an active turn 10 similar tothat shown in the above figures, but with the section 10 d being loweredto be proximate the journal 102, such as approximately the sameproximity as turn 20 c, in order to force the current to return throughthe journal 102. This embodiment may be employed for hardening recesses110 having only one undercut fillet 104, which is heated via thetranslatable passive turn portion 20 c, while the journal 102 is heatedvia the active turn 10 as described in the above embodiments.

The above described apparatus 2 is particularly suitable for variousinduction heating processes. The disclosure provides an exemplaryprocess for hardening undercut fillets 104 of a workpiece 100, which mayemploy the described apparatus 2 or which may be used in conjunctionwith other apparatus. The process includes translating a coil assembly 4radially toward a recess 110 in the workpiece 100 such that a passiveturn 20 of the coil assembly 4 clears a sidewall 108 of the recess 110and at least one crossover section 10 c, 10 e of an active coil 10 ofthe coil assembly 4 is proximate a journal area 102 in the workpiecerecess 110. The process also includes translating the passive turn 20relative to the active turn 10 such that a passive coupling section 20 aof the passive turn 20 is proximate to and electromagnetically coupledwith an active coupling section 10 b, 10 f of the active turn 10 and apassive heating section 20 c of the passive turn 20 is located at leastpartially within an undercut fillet area 104 of the workpiece recess110, and energizing the active turn 10 with electrical power to heat atleast a portion of a journal area 102 in the workpiece recess 110 usingthe at least one crossover section 10 c, 10 e of the active coil 10 andto induce electrical current in the passive turn 20 to heat at least aportion of the undercut fillet area 104 of the workpiece recess 110using the passive heating section 20 c of the passive turn 20. Incertain embodiments, the translation of the passive turn 20 relative tothe active turn 10 comprises translating the passive turn 20 in adirection parallel to a longitudinal axis 8 of the workpiece 100.

The above examples are merely illustrative of several possibleembodiments of various aspects of the present disclosure, whereequivalent alterations and/or modifications will occur to others skilledin the art upon reading and understanding this specification and theannexed drawings. In particular regard to the various functionsperformed by the above described components (assemblies, devices,systems, circuits, and the like), the terms (including a reference to a“means”) used to describe such components are intended to correspond,unless otherwise indicated, to any component, such as hardware,software, or combinations thereof, which performs the specified functionof the described component (i.e., that is functionally equivalent), eventhough not structurally equivalent to the disclosed structure whichperforms the function in the illustrated implementations of thedisclosure. In addition, although a particular feature of the disclosuremay have been illustrated and/or described with respect to only one ofseveral implementations, such feature may be combined with one or moreother features of the other implementations as may be desired andadvantageous for any given or particular application. Also, to theextent that the terms “including”, “includes”, “having”, “has”, “with”,or variants thereof are used in the detailed description and/or in theclaims, such terms are intended to be inclusive in a manner similar tothe term “comprising”.

1. A method of hardening a workpiece using induction heating, the methodcomprising: translating a coil assembly toward the workpiece;translating a passive turn of the coil assembly relative to an activeturn of the coil assembly such that a passive coupling section of thepassive turn is electromagnetically coupled with an active couplingsection of the active turn; energizing the active turn with electricalpower to induce electrical current in the passive turn to heat at leasta portion of the workpiece using a passive heating section of thepassive turn.
 2. The method of claim 1, wherein translating the coilassembly toward the workpiece comprises translating the passive turn andthe active turn radially toward a longitudinal axis of the workpiece. 3.The method of claim 2, wherein translating the coil assembly toward theworkpiece comprises translating at least a portion of the passive turninto a recess in the workpiece.
 4. The method of claim 1, wherein thecoil assembly is translated toward the workpiece such that at least aportion of the passive turn of the coil assembly clears a sidewall of arecess in the workpiece.
 5. The method of claim 1, wherein translatingthe coil assembly toward the workpiece comprises translating at least aportion of the passive turn into a recess in the workpiece.
 6. Themethod of claim 5, wherein translating the passive turn relative to theactive turn comprises translating the passive turn in a directionparallel to a longitudinal axis of the workpiece.
 7. The method of claim5, wherein translating the passive turn relative to the active turncomprises translating at least a portion of the passive heating sectionof the passive turn within an undercut area of the recess in theworkpiece.
 8. The method of claim 5, wherein translating the passiveturn relative to the active turn comprises translating at least aportion of the passive heating section of the passive turn toward anundercut area of the recess in the workpiece.
 9. The method of claim 8,further comprising deenergizing the active turn and translating the coilassembly away from the workpiece after at least a portion of theworkpiece has been heated using the coil assembly.
 10. The method ofclaim 9, further comprising translating the passive turn away from theundercut area of the recess prior to translating the coil assembly awayfrom the workpiece.
 11. The method of claim 5, further comprisingdeenergizing the active turn and translating the coil assembly away fromthe workpiece after at least a portion of the workpiece has been heatedusing the coil assembly.
 12. The method of claim 11, further comprisingtranslating the passive turn away from the recess of the workpiece priorto translating the coil assembly away from the workpiece.
 13. The methodof claim 1, further comprising deenergizing the active turn andtranslating the coil assembly away from the workpiece after at least aportion of the workpiece has been heated using the coil assembly. 14.The method of claim 13, further comprising translating the passive turnaway from a recess of the workpiece prior to translating the coilassembly away from the workpiece.
 15. The method of claim 13, whereintranslating the passive turn relative to the active turn comprisestranslating at least a portion of the passive heating section of thepassive turn toward an undercut area of a recess in the workpiece. 16.The method of claim 1, wherein translating the passive turn relative tothe active turn comprises translating at least a portion of the passiveheating section of the passive turn toward an undercut area of a recessin the workpiece.
 17. The method of claim 1, wherein translating thepassive turn relative to the active turn comprises translating at leasta portion of the passive heating section of the passive turn within anundercut area of a recess in the workpiece.
 18. A method of hardening aworkpiece using induction heating, the method comprising: translating acoil assembly toward the workpiece; translating a passive turn of thecoil assembly relative to an active turn of the coil assembly toward anundercut area of a recess in the workpiece; energizing the active turnwith electrical power to induce electrical current in the passive turnto heat at least a portion of the workpiece using a passive heatingsection of the passive turn.
 19. The method of claim 18, whereintranslating the coil assembly toward the workpiece comprises translatingat least a portion of the passive turn into the recess in the workpiece.20. A method of hardening a workpiece using induction heating, themethod comprising: providing a coil assembly including an active turnand a passive turn electrically isolated from one another andtranslatable relative to one another; translating the coil assemblytoward the workpiece while the passive turn is in a first positionrelative to the active turn such that at least a portion of the passiveturn of the coil assembly clears a portion of the workpiece; translatingthe passive turn relative to the active turn toward an undercut area ofthe workpiece; energizing the active turn with electrical power toinduce electrical current in the passive turn to heat at least a portionof the workpiece.